“Fish gotta swim, birds gotta fly,” Jerome Kern wrote in a Broadway love song—but while it’s sweet as a lyric, it’s not entirely true.

Not only are there plenty of awesome birds that can’t fly, like ostriches and penguins, but a number of fish don’t swim as well as you’d think. That made us wonder: Why is it that some fish wouldn’t medal in swimming?

It turns out they all have their reasons for investing their energy elsewhere.

When it comes to fish, “slow swimmers tend to be those that don’t need to swim quickly or efficiently,” says Selina Heppell, head of the department of fisheries and wildlife at Oregon State University. This includes ambush predators that get the jump on